2002 ISUZU AXIOM check engine

6E±208
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:

Poor connection at PCM ± Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.

Damaged harness ± Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
display on the Tech 2 while moving connectors and
wiring harnesses related to the sensor. A change in the
display will indicate the location of the fault.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.2. The HO2S should be allowed to cool before
performing this test. If the HO2S heater is
functioning, the signal voltage will gradually increase
or decrease as the sensor element warms. If the
heater is not functioning, the HO2S signal will
remain near the 450 mV bias voltage.
4. Ensures that the ignition feed circuit to the HO2S is
not open or shorted. The test light should be
connected to a good chassis ground, in case the
HO2S low or HO2S heater ground circuit is faulty.
5. Checks the HO2S heater ground circuit.
6. Checks for an open or shorted HO2S heater
element.
10.An open HO2S signal or low circuit can cause the
HO2S heater to appear faulty. Check these circuits
before replacing the sensor.
DTC P0155 ± HO2S Heater Circuit Open Bank 2 Sensor 1

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2NOTE: If the engine has just been operating, allow the
engine to cool for at least 15 minutes before
proceeding.
1. Remove the fuel pump relay.
2. Connect a fused jumper at the fuel pump relay
socket, between the battery positive at the relay and
the relay wire that leads to the fuel pump and HO2S
fuses.
3. Ignition ªOFFº.
4. Install a Tech 2.
5. Ignition ªONº, engine ªOFFº.
6. Monitor the Bank 1 HO2S 1 voltage for several
minutes.
Did the HO2S voltage go from bias voltage to above or
below the specified value?
Above
650 mV or
below
250 mV
Refer to
Diagnostic
Aids
Go to Step 3
3Inspect the fuse for the Bank 2 HO2S 1 ignition feed.
Is the fuse open?
ÐGo to Step 15Go to Step 4
41. Ignition ªOFFº.
2. Raise the vehicle.
3. Disconnect the Bank 2 HO2S 1 electrical connector.
4. Using a test light connected to a known good ground
(do not use Bank 2 HO2S 1 heater ground or Bank 2
HO2S 1 low), probe the ignition feed circuit at the
Bank 2 HO2S 1 electrical connector (PCM harness
side).
Does the test light illuminate?
ÐGo to Step 5Go to Step 7
5Connect the test light between Bank 2 HO2S 1 ignition
feed and Bank 2 HO2S 1 heater ground.
Does the test light illuminate?
ÐGo to Step 6Go to Step 8

6E±209
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0155 ± HO2S Heater Circuit Open Bank 2 Sensor 1

 
StepNo Ye s Value(s) Action
61. Allow the HO2S to cool for at least 15 minutes.
2. Using a DVM, measure resistance between the
Bank 2 HO2S 1 ignition feed and the Bank 2 HO2S 1
heater ground at the Bank 2 HO2S 1 pigtail.
Is the HO2S resistance within the specified values?
3-6 ohmsGo to Step 9Go to Step 10
7Repair the open Bank 2 HO2S 1 ignition feed circuit to
Bank 2 HO2S 1.
Is the action complete?
ÐVerify repairÐ
8Repair the open Bank 2 HO2S 1 heater ground circuit.
Is the action complete?
ÐVerify repairÐ
91. Check for a poor connection at the Bank 2 HO2S 1
harness terminals.
2. If a poor connection is found, replace terminals.
Was a poor connection found?
ÐVerify repair Go to Step 10
10Check for a poor Bank 2 HO2S 1 signal or low circuit
terminal connection at the Bank 2 HO2S 1 harness
connector and replace terminal(s) if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 11
111. Ignition ªOFFº.
2. Disconnect the PCM and check the continuity of the
Bank 2 HO2S 1 signal circuit and the Bank 2 HO2S
1 low circuit.
3. If the Bank 2 HO2S 1 signal circuit or HO2S low
circuit measures over 5 ohms, repair open or poor
connection as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
12Check for a poor Bank 2 HO2S 1 low circuit terminal
connection at the PCM and replace the terminal if
necessary.
Did the terminal require replacement?
ÐVerify repairGo to Step 13
13Check for a poor Bank 2 HO2S 1 signal circuit terminal
connection at the PCM and replace the terminal if
necessary.
Did the terminal require replacement?
ÐVerify repair Go to Step 14
14Replace Bank 2 HO2S 1.
Is the action complete?
ÐVerify repairÐ
15Locate and repair short to ground in Bank 2 HO2S 1
ignition feed circuit and replace the faulty fuse.
Is the action complete?
ÐVerify repairÐ

6E±211
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:

Heated oxygen sensor wiring ± The sensor pigtail may
be mispositioned and contacting the exhaust system.

Poor PCM to engine grounds.

Fuel pressure ± A condition which causes a lean
exhaust can cause DTC P0157 to set. The system will
go lean if pressure is too low. The PCM can
compensate for some decrease. However, if fuel
pressure is too low, a DTC P0157 may be set. Refer
to
Fuel System Diagnosis.

Lean injector(s) ± Perform ªInjector Balance Testº.

Vacuum leaks ± Check for disconnected or damaged
vacuum hoses and for vacuum leaks at the intake
manifold, throttle body, EGR system, and PCV system.

Exhaust leaks ± An exhaust leak may cause outside air
to be pulled into the exhaust gas stream past the
HO2S, causing the DTC P0157 to set. Check for
exhaust leaks near the Bank 1 HO2S 2 sensor.

MAF sensor ± The system can go lean if the MAF
sensor signal indicates an engine airflowmeasurement that is not correct. Disconnect the MAF
sensor to see if the condition is corrected. If so, replace
the MAF sensor.

Fuel contamination ± Water, even in small amounts,
can be delivered to the fuel injectors. The water can
cause a lean exhaust to be indicated. Excessive
alcohol in the fuel can also cause this condition. Refer
to
Fuel System Diagnosis for the procedure to check
for fuel contamination.

If none of above conditions are present, replace the
affected HO2S 2.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. DTC P0157 failing during operation may indicate a
condition described in the ªDiagnostic Aidsº above.
If the DTC P0157 test passes while the Failure
Records conditions are being duplicated, an
intermittent condition is indicated.
DTC P0157 ± HO2S Circuit Low Voltage Bank 2 Sensor 2

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within the parameters specified
under ªConditions for Setting the DTCº criteria
included in Diagnostic Support.
4. Using a Tech 2, monitor Bank 2 HO2S 2 voltage.
Does the Bank 2 HO2S 2 voltage remain below the
specified value?
22 mVGo to Step 4Go to Step 3
31. Ignition ªONº, engine ªOFFº.
2. Review and record Tech 2 Failure Records data and
note parameters.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor ªDTCº info for DTC P0157
until the DTC P0157 test runs.
5. Note the test result.
Does the Tech 2 indicate DTC P0157 failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Turn the ignition ªOFFº.
2. Disconnect the PCM.
3. Check the Bank 2 HO2S 2 high and low signal
circuits for a short to ground or a short to the heater
ground circuit.
Were Bank 2 HO2S 2 signal circuits shorted?
ÐGo to Step 5Go to Step 6
5Repair the Bank 1 HO2S 2 signal circuit.
Is the action complete?
ÐVerify repairÐ

6E±212
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0157 ± HO2S Circuit Low Voltage Bank 2 Sensor 2

 
StepNo Ye s Value(s) Action
61. Ignition ªOFFº.
2. Leave the PCM and HO2S 2 disconnected.
3. Check for continuity between the high and low
signal circuits.
Was there continuity between the high and low circuits?
ÐGo to Step 7Go to Step 8
7Repair the short between the high and low circuits.
Is the action complete?
ÐVerify repairÐ
81. Ignition ªOFFº.
2. Reconnect the PCM, leave HO2S 2 disconnected.
3. Ignition ªONº.
Does the Tech 2 indicate Bank 2 HO2S 2 voltage near
the specified value?
425-475 mV
Refer to
Diagnostic
Aids
Go to Step 9
9Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to the latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ

6E±214
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:

Fuel pressure ± An excessively rich fuel mixture can
cause a DTC P0158 to be set. Refer to
Fuel System
Diagnosis.

Rich injector(s) ± Perform ªInjector Balance Testº.

Leaking injector ± Refer to
Fuel System Diagnosis.

Evaporative emissions (EVAP) canister purge ± Check
for fuel saturation. If full of fuel, check canister control
and hoses. Refer to
Evaporative Emission (EVAP)
Control System.

MAF sensor ±The system can go rich if the MAF
sensor signal indicates an engine airflow
measurement that is not correct. Disconnect the MAF
sensor to see if a rich condition is corrected. If so,
replace the MAF sensor.

Check for a leaking fuel pressure regulator diaphragm
by checking the vacuum line to the regulator for the
presence of fuel. There should be no fuel in the
vacuum line.

TP sensor ± An intermittent TP sensor output will
cause the system to go rich, due to a false indication
of the engine accelerating.

Shorted Heated Oxygen Sensor (HO2S) ± If the HO2S
is internally shorted, the HO2S voltage displayed on
the Tech 2 will be over 1 volt. Try disconnecting the
affected HO2S with the key ªONº, engine ªOFFº. If the
displayed HO2S voltage changes from over 1000 mV
to around 450 mV, replace the HO2S. Silicon
contamination of the HO2S can also cause a high
HO2S voltage to be indicated. This condition isindicated by a powdery deposit on the portion of the
HO2S exposed to the exhaust stream. If
contamination is noticed, replace the affected HO2S.

Open HO2S signal or low circuit, or faulty HO2S ± A
poor connection or open in the HO2S signal or low
circuit can cause the DTC to set during deceleration
fuel cutoff mode operation. An HO2S which is faulty
and does not allow full voltage swing between the rich
and lean thresholds can also cause this condition.
Operate the vehicle while monitoring the HO2S voltage
with a Tech 2. If the HO2S voltage is limited within a
range between 300 mV to 600 mV, check the HO2S
signal and low circuit wiring and associated terminal
connections. If the wiring and connections are OK,
replace the HO2S.

If none of above conditions are present, replace the
affected HO2S.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. DTC P0158 being set during deceleration fuel cutoff
mode operation may indicate a condition described
in the ªDiagnostic Aidsº above. If the DTC P0158
test passes while the Failure Records conditions are
being duplicated, an intermittent condition is
indicated.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
DTC P0158 ± HO2S Circuit High Voltage Bank 2 Sensor 2

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within parameters specified
under ªConditions for Setting the DTCº criteria
included in Diagnostic Support.
4. Using a Tech 2, monitor Bank 2 HO2S 2 voltage.
Does the Bank 2 HO2S 2 voltage remain above the
specified value?
952 mV
(500 mV in
deceleration
fuel cut-out
mode)
Go to Step 4Go to Step 3
31. Ignition ªONº.
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor ªDTCº info for DTC P0158
until the DTC P0158 test runs.
5. Note the test result.
Does the Tech 2 indicate DTC P0158 failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids

6E±215
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0158 ± HO2S Circuit High Voltage Bank 2 Sensor 2

 
StepNo Ye s Value(s) Action
41. Ignition ªOFFº.
2. Disconnect Bank 2 HO2S 2.
3. Ignition ªONº.
4. At the HO2S Bank 2 Sensor 2 connector (PCM
side), use a DVM to measure voltages at the high
and low signal terminals.
Are the voltages in the specified range?
3-4 VGo to Step 5Go to Step 6
5Repair short to voltage in signal circuit.
Is the action complete?
ÐVerify repairÐ
61. Ignition ªONº, engine ªOFFº.
2. At Bank 2 HO2S 2 connector (PCM side) jumper
both the HO2S high and low signal circuits (PCM
side) to ground.
3. Using a Tech 2, monitor Bank 2 HO2S 2 voltage.
Is Bank 2 HO2S 2 voltage below the specified value?
10 mVGo to Step 7Go to Step 8
71. Disconnect the jumpers to ground from Bank 2
HO2S 2 PCM-side connector.
2. With the HO2S 2 connector disconnected, monitor
Bank 2 HO2S 2 voltage.
Is Bank 2 HO2S 2 voltage between the specified
values?
425-475 mV
Refer to
Diagnostic
Aids
Go to Step 8
8Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to the latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ

6E±217
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0160 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:

Poor connection or damaged harness ± Inspect the
harness connectors for backed-out terminals,
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.

Faulty HO2S heater or heater circuit ± With the ignition
ªONº, engine ªOFFº, the HO2S voltage displayed on a
Tech 2 should gradually drop to below 250 mV. If not,
disconnect the HO2S and connect a test light between
the HO2S ignition feed and heater ground circuits. If
the test light does not light, repair the open ignition feed
or sensor ground circuit as necessary. If the test light
lights and the HO2S signal and low circuits are OK,
replace the HO2S.
Intermittent test ± With the ignition ªONº, monitor the
HO2S signal voltage while moving the wiring harness
and related connectors. If the fault is induced, the
HO2S signal voltage will change. This may help isolate
the location of the malfunction.Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. If the DTC P0160 test passes while the Failure
Records conditions are being duplicated, an
intermittent condition is indicated.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
DTC P0160 ± HO2S Circuit Insufficient Activity Bank 2 Sensor 2

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the engine above 1200 RPM for two
minutes.
Does the Tech 2 indicate Bank 2 HO2S 2 voltage
varying outside the specified values?
425-475 mVGo to Step 3Go to Step 4
31. Ignition ªONº, engine ªOFFº, review and record
Tech 2 Failure Records data and note parameters.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor ªDTCº info for DTC P0160
until the DTC P0160 test runs.
4. Note the test result.
Does the Tech 2 indicate DTC P0160 failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
4Check for a damaged harness.
Was problem found?
ÐVerify repairGo to Step 5
5Check for poor Bank 2 HO2S 2 high and low circuit
terminal connections at the Bank 2 HO2S 2 harness
connector and replace terminal(s) if necessary.
Did either terminal require replacement?
ÐVerify repairGo to Step 6
6Check for poor Bank 2 HO2S 2 high and low circuit
terminal connections at the PCM and replace terminals
if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 7

6E±218
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0160 ± HO2S Circuit Insufficient Activity Bank 2 Sensor 2

 
StepNo Ye s Value(s) Action
71. Ignition ªOFFº.
2. With the PCM disconnected, check continuity of the
Bank 2 HO2S 2 high circuit.
3. If the Bank 2 HO2S 2 high circuit measures over 5.0
ohms, repair open or poor connections as
necessary.
Was a Bank 2 HO2S 2 high circuit problem found and
corrected?
ÐVerify repairGo to Step 8
81. Ignition ªOFFº.
2. With the PCM disconnected, check continuity of the
Bank 2 HO2S 2 low circuit.
3. If the Bank 2 HO2S 2 low circuit measures over 5
ohms, repair open or poor connections as
necessary.
Was a Bank 2 HO2S 2 low circuit problem found and
corrected?
ÐVerify repairGo to Step 9
91. Ignition ªONº, engine ªOFFº.
2. Disconnect Bank 2 HO2S 2 and jumper the HO2S
high and low circuits (PCM side) to ground.
3. Using a Tech 2, monitor Bank 2 HO2S 2 voltage.
Is Bank 2 HO2S 2 voltage in the specified range?
0-10 mVGo to Step 10Go to Step 11
10Replace Bank 2 HO2S 2.
Is the action complete?
ÐVerify repairÐ
11Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to the latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ